1. Technical Field
Aspects of the present invention relate to mass spectrometers, to mobility spectrometers, and to ion sources at elevated pressures such as atmospheric-pressure sources, and more specifically, to a curtain gas filter therefor.
2. Related Art
For related art investigations of large molecules, mass spectrometers and mobility spectrometers may be used. The mass spectrometers investigate the total molecule weight, which is approximately proportional to the volume of the molecule under investigation. The mobility spectrometer investigates the speed of a charged molecule when dragged through a buffer gas, a quantity which is approximately proportional to the cross section of the molecule under investigation.
For both related art systems, the ion source is important. Commonly used ion sources for large molecules include “electrospray ion sources (ESI)” as disclosed in J. B. Fenn, JASM 4 (1993) 524 and sources for “matrix assisted laser desorbed ion sources (MALDI)” as disclosed in M. Karas, F. Hillenkamp, Anal. Chemistry 60 (1988) 2299 as well as sources for “electrospray-assisted laser desorbed ion sources (ELDI)” as disclosed in M. Z. Huang, H. J. Hsu, J. Y. Lee, J. Jeng, J. Shiea, J. Prot. Res. 5 (2006) 1107, or “desorption electrospray-ion sources (DESI)” as disclosed in Z. Takats, J. M. Wiseman, B. Gologan, G. Cooks Science 306 (2004) 471. These sources are preferentially used at elevated pressures typical at atmospheric pressure. However, other ionization methods in “atmospheric pressure ion-sources (API)” can be used as well.
Related art investigations of molecules have become important in applications related to biology, medicine and pharmacology. These related art techniques allow characterization of a molecule not only by weight and cross section but also by structure, which becomes apparent by investigating the fragments into which the molecule will break when it absorbs energy, for example, by collisions with buffer gas molecules or atoms.